Correlative thermostatic switch mechanism



Aug. 28, 1945. Q w. CRlsE 2,383,533

CORRELATIVE THERMOSTATIC SWITCH MECHANISMA FiledKSept. 18, 1943 Geoye UNIS@ y www,

Patented Aug. 28, 1945 CORRELATIVE THERMOSTATIO SWITCH CHAN! George W. Crise, Columbus, Ohio, asslgnor to Crise Electric Manufacturing Company, Columbus, Ohio, a corporation of Ohio Application september 1s, 1943, serial N6. 502,982

3 Claims.

This invention relates to an improved thermostatically actuated switch mechanism for controlling electrical circuits, having particular reference to that type of switch mechanism embodylng deflecta'ble bimetallic elements which alter in position in response to varying surrounding temperatures.

It is an object of the present invention to provide a thermostatic switch wherein is embodied a casing having an axially disposed support adapted for the reception of one end of a spiral bimetallic coil, the outer or deectable end of the coil being connected withv a ilexible reed member carrying spaced contacts, the latter :being disposed for registration with complemental contacts supported by'the casing,l the arrangement Ibeing such that as the coil responds to variations in temperature, the contacts of the flexible reed member are-progressively brought into or out of engagement with the casing carried contacts to effect the opening or closing of associated electrical circuits.

It is another object of the invention to provide a circuit-controlling'system in which a pair of correlated switch units of the character set forth are provided, the two units being disposed in zones in which diilerent temperature conditions usually prevail, and, wherein the ,fbimetaliic coil of one unit deects in responding to temperature variations in a manner opposite to that of the coil inthe other unit, the complemental casing carried contacts of the two units being electrically united, so that rwhen the reed member contacts of both units are in engagement with complemental casing carried contacts, an electrical circuit containing said units and associated equipment is closed or energized.

`While the thermostatic switch apparatus comprising the present invention may be employed in many diiferent capacities, one of its uses is that of controlling the operation of the motors of Ventilating fans, particularly the so-called attic type of fan now widely used in Ventilating residential buildings.

At present, it is customary to control the motor of such a Ventilating fan by means of a, manual switch or through a clock operated switch. A unique problem is involved in effecting proper control of an attic fan because of the fact that sidetemperature, such as usually occurs at night. Obviously, the fan should be run only when (Cl. 20o-138) the house is too warm for comfort and'then only if the outside temperature is lower than that inside the house. It is further obvious that these conditions occur under dinerent weather conditions at diiferenttimes of thev day and night, which makes the use of a, time or clock-controlled switch generally unsatisfactory and, of course, the manual switch, like any other hand control requires an understanding operator to obtain correct operation as well as the continued presence of the operator.

In its adaptation to attic fan control, the present invention employs two similar but novel thermostatic switch units which operate in conjunction with each other, one of the switch units being placed in an outdoor location and the* other within the house containing the fan. the units being of such construction that when the outdoor temperature falls below that prevailing within the house, the motor circuit of the fan is completed. When the indoor and outdoor temperatures are substantially equivalent, the motor circuit will be opened, and if the indoor temperature rises above that prevailing out of doors, the

' motor circuit will likewise be completed. By this tion, of the thermostatic switch apparatus comprising the present nventlon;

Fig. 2 is a transverse sectional view taken on the plane indicated by the line lI--II of Fig. 1.

Referring more particularly to the drawing, there is disclosed at A a thermostatic switch unit adapted to foe located outside the house in a protected position, said unit consisting of a circular casing 5 formed from insulating material and having a lback wall 6, an annular side wall-1 and a removable front wall 8, the latter being provided with one or more openings for the ventilation of the interior of the casing.

Mounted axially within the casing li is a supporting post 8,`the end portions of the post being rotatably received within bearing-affording openings donned in the back and front walls B and 8, respectively. Secured to the post i is one end of a spiral bimetallic coil I0, the latter having its high expanding metal on the outside of the spiral, so that the coil unwinds as it cools. The outer or deectlng end of the coil has fastened thereto, by means oi a block I I and a rivet I2, one end oi' a flexible spring steel reed I3, the opposite end of said reed being connected by means of a rivet and insulating block I4 with the inner surface of the annular casing wall 1. The reed carries at spaced intervals a plurality ot contacts indicated at lia, 15b, lic, lid and lle which are movable with the reed in response to temperature induced deilection of the coil i0.

Disposed in registration with the contacts Ila to 15e, inclusive, is a series of casing carried contacts designated at Ita, 1Gb, itc, lid and ite which, in this instance, comprise adjustable screws threaded into openings formed.- at intervals in the annular wall 1. 'I'he inner ends of the contacts lia to lie, inclusive, are positioned so that they may be progressively engaged or disengaged by the reed contacts lia. to lie as unwinding or winding movement is imparted to the coil i as a result o! temperature variations. 'Ihe operating range o! the thermostat may be varied by connecting with one end of the post 9 a manually movable indicator hand I1. The pointer, at the outer end of this hand, is movable over a graduated surface il provided at one side of the front wall 8 contiguous to its peripheral edge.

A complemental thermostatic switch unit B is used in connection with the unit A but occupies an indoor location. The construction oi the unit B is the same as that o! the unit A, with the exception that its spiral thermostatic coil lllb has its high-expanding metal on the inside of the coil, so that the latter unwinds as it warms. Also, the graduations and markings l8b o! the unit B are reversed in order with respect to the graduations and markings 18a of the unit A.

The reed Hb of the unit B also carries spaced carried thereby are connected through the ran 2l with the source oi power so that whenever any of the contacts of the reed Ilis connected to a concontacts.

stationary contacts 20a, 20h, 20c, 2M and 20e which are adapted for successive and progressive engagement or disengagement with the inner ends of stationary but adjustable contacts 2id, 2lb, 2Ic, 2id and Zie carried by the annular wall of the casing.

The contacts lGa and 21a of the units A and B are united by a conductor 22a; the contact l6b is united with the contact 2lb by a conductor 22o; the contact itc with the contact 2Ic by a conductor 22e; the contact ISd with the contact 2id by a conductor 22d; and the contact lie is electrically united with the contact Zie by a conductor 22e. In this instance, the post 9 of the unit A is united by a conductor 23 with the electric motor 24 of a Ventilating fan 25, the latter being shown as mounted in an opening 28 extending through an attic ooring. whereby when the fan is in operation, vitiated air may be withdrawn from the lower iloors of a building and discharged to the atmosphere through the opening 26 and other associated vents (not shown). A conductor 21 extends from the motor 2l to a source of electrical energy 28, such as a commercial house circuit, while another conductor 29 extends from the source 28 to the post Ib of the unit B.

In the operation o! the apparatus, it will be noted that the inside thermostatic unit B has its bimetallic coil lib wound with the high-expanding vmetal on the inside oi the coil, hence, the coll ilb unwinds as the ambient temperature increases, thereby causing the reed contacts 20a to 20e, inclusive, to engage in consecutive and progressive order the casing contacts 22a to 22e, inclusive. It will also lbe noted that the flexible reed in each thermostatic unit and the contacts This condition would be typical of an ordinary evening Just before operation of the fans should start, with both outside and inside temperatures about 80 F. As the outside temperature continues to fall, the thermostatic unit A will close the contacts llb and IIb, which will complete the circuit through conductor 22h, contacts 2lb and 2lb to the source of current supply, starting the ian. As the ian operates, cool air from the outside will cool the house slowly and the inside thermostatic unit, in response to such a temperature drop, will respond to break the circuit through contacts 2lb and 2lb. This will stop the ian unless a continued drop in outside temperature results in cooling the thermostatic unit A to such an extent that engagement is effected between the contacts lia and Ila.

Under these circumstances, the fan would continue to operate through contacts 20a and 2id of the unit B, such operation being sustained until a further drop in house temperature iiexes the coil Ib and moves its associated reed IIb to break engagement between the contacts 20a and 2 Ia This minimum temperature may be selected by setting the pointer of the indicator Hb to any desirable temperature, for example 75 F.,

so that the fan would remain idle until the next day, when a rise in temperature would reestablish the contacts 20a, 2Ia, 2Gb and 2lb, 20c and Zic, 2id and .2id and 28e and 21e in their order, depending on how warm the daydeveloped to be.

The ian, however, would not start because the thermostatic unit A, being outside, would warm more quickly than the inside unit B, and to break the correspondingly connected contacts comprising the groups indicated at I5 and I6 in the same order and at'temperatures selectable by the adjustment of the hand I1. However, a sudden cooling of the outside, such as the result of a thunder shower, would reestablish the contacts Ita to ISe, inclusive, so that the operation of the fan would start as soon as the outside temperature fell below the house temperature, regardless of the time of day, but providing the inside temperature was above F. or other selected temperature.

Consideration of the above will disclose that my improved thermostatic control system takes advantage of every opportunity to bring cool outside air into the house but always precluding fan operation when the outside air is too warm to be benecial and likewise arresting fan operation whenever the interior temperature of the house is at a comfortable level.

I claim:

1. A thermostatic switch comprising a casing having an internal substantially circular chamber, an axially arranged post carried by said casing, a spiral thermostatic coil deiectable in response to temperature variations, said coil being positioned in said casing chamber and having its assasss inner end fixed to said support, an arcuate ilex-l ible reed having one end secured to the outer deilectable end of said coil and its other end stationarily secured to said casing, a plurality of spaced contacts carried by said reed, and a plurality of spaced complemental contacts carried by said casing in registration with the reed contacts, the casing contacts being progressively engaged orl disengaged by the reed contacts upon predetermined variations in 4the temperature around the coil.

2. A thermostatic switch comprising a casing, an axially arranged post carried by said casing having a. substantially circular chamber, a spiral thermostatic coil defiectable in response to temperature variations, said coil being positioned in said casing chamber and having its inner end iixed to said support, an arcuate ilexible reed having one end secured to the outer deiiectable end lof said coil and its other end stationarily secured to said casing, a plurality of spaced contacts carried by said reed, a plurality of spaced complemental contacts carried by said casing in registration with the reed contacts, the casing contacts being progressively engaged or disengaged by the reed contacts upon predetermined variations in the temperature around thel coil, and manually operated means accessible exteriorly of the casing for rotatably adjusting said post to vary the operating positions of the coil and the reed, whereby to control `the temperature range at which said contacts are brought into and out of relative engagement.

3. A thermostatic switch comprising a casing having an inner chamber formed with an 'annular outer wall, an axially arranged rotatably adjustable support carried by said casing and positioned axially of said chamber, a spiral thermostatic coil deectable in response to temperature variations, said coil being positioned in said chamber and having its inner end xed to said support, an arcuate flexible reed having one end y reed, said contacts being progressively engaged by the reed upon predetermined variations in the temperature around said coil.

GEORGE W. n CRISE. 

